An internal gear machine can be or is preferably driven optionally or depending on the direction of rotation as an internal gear pump by means of the electric motor or the electric motor can be or is driven as a current generator by means of the internal gear machine. A motor pump unit such as this can be used, for example, to drive a highly dynamic hydraulic axis.
What matters in such motor pump units is a high dynamic, low noise and pulsation level, recoverability, long service life, freedom from leaks, long service life and insensitivity to shock, dirt, and water, in particular salt water, and temperature, in particular cold.
In the motor pump units known until now, a drop in conveyance of pressurizing medium and consequently a strong discontinuity of the pressurizing medium volume flow can occur in the highly dynamic reverse operation during the respective reversal of direction of rotation.